Individual iron club heads in a set typically increase progressively in face surface area and weight as the clubs progress from the long irons to the short irons and wedges. Therefore, the club heads of the long irons have a smaller face surface area than the short irons and are typically more difficult for the average golfer to hit consistently well. For conventional club heads, this arises at least in part due to the smaller sweet spot of the corresponding smaller face surface area.
To help the average golfer consistently hit the sweet spot of a club head, many golf clubs are available with cavity back constructions for increased perimeter weighting. Perimeter weighting also provide the club head with higher rotational moment of inertia about its center of gravity. Club heads with higher moment of inertia have a lower tendency to rotate caused by off-center hits. Another recent trend has been to increase the overall size of the club heads. Each of these features increases the size of the sweet spot, and therefore makes it more likely that a shot hit slightly off-center still makes contact with the sweet spot and flies farther and straighter. One challenge for the golf club designer when maximizing the size of the club head is to maintain a desirable and effective overall weight of the golf club. For example, if the club head of a three iron is increased in size and weight, the club may become more difficult for the average golfer to swing properly.
In general, to increase the sweet spot, the center of gravity of these clubs is moved toward the bottom and back of the club head. This permits an average golfer to launch the ball up in the air faster and hit the ball farther. In addition, the moment of inertia of the club head is increased to minimize the distance and accuracy penalties associated with off-center hits. In order to move the weight down and back without increasing the overall weight of the club head, material or mass is taken from one area of the club head and moved to another. One solution has been to take material from the face of the club, creating a thin club face. Examples of this type of arrangement can be found in U.S. Pat. Nos. 4,928,972, 5,967,903 and 6,045,456.
However, for a set of irons, the performance characteristics desirable for the long irons generally differ from that of the short irons. For example, the long irons are more difficult to hit accurately, even for professionals, so having long irons with larger sweet spots is desirable. Similarly, short irons are generally easier to hit accurately, so the size of the sweet spot is not as much of a concern. However, greater workability of the short irons is often demanded.
Fine tuning the center of gravity and moment of inertia properties is difficult to achieve while simultaneously attempting to capture within a set of clubs a continuous aesthetic look and feel. Currently, in order to produce the best overall game results, golfers may have to buy their clubs individually, which results in greater play variation through the set than is desirable. Additionally, if different clubs from different manufacturers are used, any given club within a piecemeal set could have the correct playing standards but lack the desired feel for a golfer. Therefore, there exists a need in the art for a set of clubs where the individual clubs in the set are designed to yield an overall maximized performance continuum for the set while maintaining a consistent aesthetic look and feel during play.